I would find it confusing if costumes would be messed up between archer-swordsman-priest-wizard but how about being able to wear all costumes for your class without the need to pick certain rank up to get its costume? Messing up your build just for the costumes isn’t fun, but seeing cool costumes not avialable to your build is saddening.
Imo each rank up should give players all costumes available for their class choice when they rank up, not just the chosen one. For example your archer got to rank 2 and you would receive ranger and quarrel shooter costumes, even if you continue to be archer c2 or even if you pick ranger class you’d still get quarell shooter costume as bonus. But you obviously won’t be able to pick priest, wizard or swordsman costumes as they are not available in your ranking up.